JP2010081750A - Motor control circuit ad motor device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new motor control circuit and a motor device wherein a switching starting position is precisely detected even when the position detection result of a rotor 10 is not an ideal duty of 50%. <P>SOLUTION: The time of a rotation cycle of the rotor 10 is measured by a counter, and based on the time of one rotation cycle of the rotor and the time required for soft switching just before calculation, the soft switching starting position is calculated with a time reference obtained by dividing one rotation cycle of the rotor by the number of poles of the rotor. As a result, the soft switching starting position is precisely detected even when a position detection signal does not become an output of the ideal duty of 50%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control circuit including a means for detecting a soft switching start position for smoothly changing a coil current, and a motor device including the motor control circuit.

In general, a fan motor used in an OA device rotates at full speed while the device is operating, and often rotates at a low speed during standby to reduce noise and power consumption of the fan motor.
When the fan motor is operated at low speed, the wind noise caused by the blades is reduced, but the vibration noise and electromagnetic noise of the fan motor are emphasized.
In order to reduce the vibration noise and electromagnetic noise, soft switching control is often performed in which an inclination is generated at the rise and fall of the coil current to smoothly change the coil current.

However, in the fan motor drive, when the coil current is tilted by digital control, the switching of the energization direction is delayed for the time from when the coil current starts to decay until it becomes zero.
The delay in switching the energization direction causes torque in the direction opposite to the rotor rotation direction, which causes vibration noise and deterioration in efficiency.
As a countermeasure against vibration noise and efficiency reduction due to the delay in switching the energization direction, there is an advance angle setting method in which a rotor position detection sensor (for example, a hall element) is arranged on the same circumference in the direction opposite to the rotor rotation direction.

If this advance angle setting method is used, the soft switching start position can be advanced to reduce the delay in switching the energization direction, and vibration noise can be reduced and efficiency can be improved. There are many cases where corners cannot be provided.
For this reason, a method for detecting the soft switching start position using a time immediately before a half cycle of the rotor position detection signal has been proposed as a method for speeding up the soft switching start position without requiring advance angle setting (for example, , See Patent Document 1 below).

FIG. 9 is a diagram showing an outline of the soft switching start position detecting operation in this conventional method. In the following description, a case will be described in which a single-phase full-wave brushless DC motor having a rotor composed of two pairs of four poles of N pole and S pole is used.
A single-phase full-wave brushless DC motor has a structure including a motor coil in which a copper wire is wound N times around a stator having a bearing in a rotor in which permanent magnets are combined in a cylindrical shape.
One Hall element is provided inside the rotor, and the magnetic pole variation of the rotor is detected by the Hall element to detect the position of the rotor.

The rotor position detection signal S10 is a signal obtained by detecting the position of the rotor based on the magnetic field detected by the Hall element, and two cycles of the rotor position detection signal S10 correspond to one rotation of the rotor.
As shown in the figure, in the conventional method, a half-cycle time T4 of the rotor position detection signal S10 is continuously measured using a clock, and a time T5 is calculated using the last half-cycle time T4. Here, the time T5 is set so as to start from the changing point of the rotor position detection signal S10, and to end after a certain period (for example, about 75% as shown in the figure) with respect to the time T4 of the immediately preceding half cycle. Is done.

Then, the soft switching start position signal S16 is generated so that the position (time) at which the time T5 ends becomes the soft switching start position.
By using the soft switching start position signal S16 as a rotor position detection signal instead of the original rotor position detection signal S10 and driving the motor by a motor control circuit having soft switching control, a coil as shown in FIG. A current ICOIL can be obtained.
As described above, in the conventional motor control, by calculating the time T5, an appropriate position for starting soft switching is detected to reduce vibration noise and increase efficiency.
JP 2007-174778 A

However, the above conventional method has the following problems.
That is, when the rotor position detection signal does not become an ideal duty 50% output, such as when the magnetization of the rotor magnetic poles is not uniform, or when the Hall element used for rotor position detection is offset, the soft switching start position is detected. The accuracy is deteriorated, and vibration noise and efficiency are deteriorated.
Here, FIG. 10 is a diagram showing an outline of the soft switching start position detecting operation which is a problem in the conventional method.
As shown in the figure, in the conventional method, since the soft switching start position is detected using the time T4 immediately before the half cycle of the rotor position detection signal S10, the duty of the rotor position detection signal S10 is shifted. The soft switching start position detection signal S16 is an output in which the duty is further shifted.

  More specifically, when the duty of the rotor position detection signal S10 is not 50%, the time T5 set by using the half-cycle time T4 is a constant ratio with respect to the time T4, and a short half-time. Since the calculation is performed using the time T4 at the time of the long half cycle at the time of the cycle, and the calculation is performed using the time T4 at the time of the short half cycle at the time of the long half cycle, the soft switching start position detection signal S16 is The output is such that the duty is shifted more than the shift of the duty of the position detection signal S10.

Therefore, when the motor control is performed using the soft switching start position detection signal S16, the coil current ICOIL flowing through the motor coil 13 in FIG. 1 becomes a current waveform as shown in FIG. Incurs efficiency degradation.
Therefore, the present invention has been made in view of the above circumstances, and its purpose is to accurately start soft switching even when the position detection signal does not become an ideal duty 50% output in a motor control circuit having soft switching control. A novel motor control circuit capable of detecting a position and a motor device including the same are provided.

In order to solve the above problems, the first invention
A motor control circuit comprising means for detecting a soft switching start position based on a detection result of a magnetic pole of a rotating rotor, wherein the soft switching start position detection means is based on a detection result of the magnetic pole of the rotor. The motor control circuit is characterized in that the time of the rotor rotation cycle is measured, and the soft switching start position is detected based on the measured time of the rotor rotation cycle and the time required for soft switching.

In addition, the second invention,
In the first invention, the soft switching start position detecting means divides the time of one rotation period of the rotor equally by the number of poles of the magnetic poles of the rotor, and the soft switching start position based on the equally divided unit time. It is a motor control circuit characterized by detecting.
In addition, the third invention,
In a second aspect of the present invention, the soft switching start position detecting means detects a time when 70 to 80% has elapsed from the first time of the equally divided unit time as the soft switching start position. It is.
In addition, the fourth invention is
A motor device comprising the motor control circuit according to any one of the first to third inventions.

According to the present invention, since the soft switching start position is detected based on the time of the rotation period of the rotor and the time required for the soft switching, even when the rotor position detection signal does not become an ideal duty 50% output, it is accurate. The soft switching start position can be detected.
As a result, when the motor device of the present invention is applied to a fan motor or the like, it is possible to avoid vibration noise and deterioration of efficiency during operation of the fan motor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the same parts as those in the other drawings are denoted by the same reference numerals.
(Example of motor configuration)
1 and 2 are schematic views showing an embodiment of a motor device 100 according to the present invention.
The motor device 100 includes a single-phase full-wave brushless DC motor M as shown in FIG. 1 and a motor control circuit (controller) C configured as shown in FIG.
First, as shown in FIG. 1, this single-phase full-wave brushless DC motor M is mainly composed of a magnet rotor 10 formed by combining permanent magnets in a cylindrical shape, and a motor coil 13 having a bearing 11 in the center. The magnet rotor 10 rotates around the motor coil 13 (outer rotor type).

The magnet rotor 10 has a structure in which four pairs of permanent magnets (N poles and S poles) in total (four poles) are arranged in an annular shape inside the cup-shaped rotor main body and have four magnetic poles. .
On the other hand, the motor coil 13 has a structure in which four arms of a stator 12 having a cross-shaped cross section having a bearing 11 at the center are each wound with a copper wire (winding) wound N times.

Further, one Hall element 14 is provided inside the rotor 10.
The Hall element 14 detects the magnetic pole variation of the rotor 10 accompanying the rotation of the motor coil 13 to detect the position of the rotor 10, and the detected rotor position is used as a rotor position detection signal S10 as shown in FIG. Output to the motor control circuit C.
The rotor position detection signal S10 is a signal obtained by detecting the position of the rotor 10 based on the magnetic field detected by the Hall element 14, and two cycles of the rotor position detection signal S10 correspond to one rotation of the rotor 10.

(Configuration example of soft switching start position detection circuit)
Next, FIG. 2 is a block diagram showing a configuration example of the motor control circuit C.
As shown in the figure, the motor control circuit C includes a rotor position detection circuit 20, an oscillator 21, a single rotation edge detection circuit 22, a single rotation cycle counter circuit 23, a single rotation cycle register circuit 24, a software A switching start position calculation circuit 25 and a soft switching start position detection circuit 26 are mainly configured.
Then, the rotor position detection circuit 20 outputs a rotor position detection signal S10 based on the magnetic field detected by the Hall element 14, and the oscillator 21 generates a clock signal S11 that determines the operation timing of the entire circuit.

The one-rotation edge detection circuit 22 detects an edge of one rotation of the rotor 10 based on the rotor position detection signal S10 output from the rotor position detection circuit 20, and outputs an edge detection signal S12.
The one rotation cycle counter circuit 23 is reset when the edge detection signal S12 output from the one rotation edge detection circuit 22 is at the H level (high level), and counts up when the edge detection signal S12 is at the L level (low level). The period of one rotation is measured based on the clock signal S11.

The one rotation period register circuit 24 records and updates the value S13 measured by the one rotation period counter circuit 23 when the edge detection signal S12 is at the H level, and holds the measurement value S13 of one rotation period of the rotor 10.
The soft switching start position calculation circuit 25 calculates the soft switching start position based on the value S14 of the period of one rotation of the rotor 10 recorded in the one rotation period register circuit 24.
The soft switching start position detection circuit 26 outputs a soft switching start position signal S16 based on the calculation result S15 of the soft switching start position calculation circuit 25.

(Configuration example of rotor 1 rotation edge detection circuit 22)
Next, FIG. 3 is a diagram showing a configuration example of the one-rotation edge detection circuit 22 among the circuits constituting the motor control circuit C.
As shown in the figure, this one-rotation edge detection circuit 22 is composed of three flip-flop circuits 30, 31, 32, three AND circuits 33, 34, 35, and one selector circuit 36. Yes. When the signal input to the selector circuit 36 as the selection signal S is H level, the input signal A is output as the output signal Q. When the signal input as the selection signal S is L level, the input signal B is output as the output signal Q.

FIG. 4 is a timing chart showing the operation of the one-rotation edge detection circuit 22 shown in FIG. Here, the flip-flop circuits 30 and 31 in FIG. 3 have a shift register configuration, and the normal output S22 of the flip-flop circuit 31 is the period of the clock signal S11 from the normal output S20 of the flip-flop circuit 30. The output is shifted by only. Similar output is obtained for the inverted outputs S21 and S23.
As shown in FIG. 4, the output S24 of the AND circuit 34, which is the logical product of the inverted output S21 of the flip-flop circuit 30 and the normal output S22 of the flip-flop circuit 31, is clocked at the falling edge of the rotor position detection signal S10. It becomes H level for one cycle of the signal S11.

Similarly, the output S28 of the AND circuit 33 that is the logical product of the normal output S20 of the flip-flop circuit 30 and the inverted output S23 of the flip-flop circuit 31 is one cycle of the clock signal S11 at the rising edge of the rotor position detection signal S10. Minute, H level.
The selector circuit 36 uses the output S24 of the logical product circuit 34 as a selection signal. When the output S24 of the logical product circuit 34 is at the H level, the inverted output S26 of the flip-flop circuit 32, and when the output S24 is at the L level, the positive output of the flip-flop circuit 32 is obtained. The force S25 is output as the output signal S27.

Therefore, the normal output S25 of the flip-flop circuit 32 is an output that is inverted at every falling edge of the rotor position detection signal S10 as shown in FIG.
The rotor 1 rotation edge detection signal S12 is an output of the logical product circuit 35 that is a logical product of the signal S28 that detects the rising edge of the rotor position detection signal S10 and the signal S25 that is inverted every falling edge of the rotor position detection signal S10. Become.
Note that the rising edge of the rotor position detection signal S10 and the rising edge of the rotor 1 rotation edge detection signal S12 are shifted by one cycle of the clock signal S11, but the cycle of the clock signal S11 is sufficiently shorter than the rotor position detection signal S10. Thus, the measurement error of the measured value S13 of the rotor 1 rotation period can be reduced.

  In the above description, the rotor 1 rotation edge is detected based on the rising edge of the rotor position detection signal S10. However, the output signal S28 of the AND circuit 33 in FIG. By calculating the logical product of the output signal S24 of the logical product circuit 34 and the normal output S25 of the flip-flop circuit 32, it is possible to detect the rotor 1 rotation edge with reference to the falling edge of the rotor position detection signal S10.

(Configuration example of soft switching start position calculation circuit)
FIG. 5 is a diagram showing a configuration example of the soft switching start position calculation circuit 25 in the motor control circuit C shown in FIG.
As shown in the figure, this soft switching start position calculating circuit 25 shifts the measured value S14 of one rotation period to the lower bit side and outputs a plurality of bit shift circuits (for example, 5-bit 1-bit shift). In the case of a circuit, if binary 11111 is input, the output is 01111) 40, 41, 42, 43, 44, a plurality of selector circuits 45, 46, 47, 48, an adder circuit 49, and soft switching And a start position setting circuit 50.

The bit shift circuits 40, 41, 43, and 44, except for the bit shift circuit 42, perform 1-bit shift, 2-bit shift, 3-bit shift,. The value is output as a value of 1 / M to the power of M,.
The selector circuits 45, 46, 47, and 48 select signals S36 [0], S36 [1], S36 [2],..., S36 [M] of each bit of the output S36 of the soft switching start position setting circuit 50. As a signal, the selector circuit whose selection signal is H level outputs the output of the bit shift circuit inputted to the input A, and the selector circuit whose selection signal is L level outputs all the bits L level from the output Q.

The adder circuit 49 adds all the output values of the selector circuits 45, 46, 47, and 48 and outputs the result as an addition result value S35.
Since soft switching is performed every quarter rotation of the rotor, the bit shift circuit 42 shifts the value of the addition result S35 by 2 bits to the lower bit side, and starts soft switching of the quarter value of the addition result S35. Output as position calculation result S15.
Therefore, when it is desired to set the soft switching start position to a position that is 75% of the rotor quarter rotation cycle, only the select signals S36 [0] and S36 [1] of the selector circuits 45 and 46 are soft-switched. The start position setting circuit 50 may set it.

If the soft switching start position is to be 87.5% of the rotor quarter rotation cycle, the select signals S36 [0], S36 [1], S36 [2] of the selector circuits 45, 46, 47 are used. Only a value that becomes H level may be set by the soft switching start position setting circuit 50.
Here, the soft switching start position setting circuit 50 can be set by a register having an external input or a nonvolatile memory, so that the soft switching start position can be easily changed, and the maximum value is , The measured value S13 of the rotor quarter rotation period is 1/2 of the power of 2 + 1 +2 of the square of 2 + 1 of the power of 3 + 1 of the M power of +2 and the resolution is the rotor of 4 minutes It becomes 1 / M power of 2 of the measured value S13 of one rotation period.

  In the above description, the soft switching start position can be easily changed by setting the soft switching start position setting circuit 50. However, when the soft switching start position may be fixed, the selector circuits 45 and 46 are used. , 47 and 48 and the soft switching start position setting circuit 50 are not necessary, and a bit shift circuit necessary for calculation (for example, bit shift circuits 40 and 41 in the case of 75% of the rotor quarter rotation period); The circuit can be simplified by the addition circuit 49 and the bit shift circuit 42 for obtaining a quarter value of the addition result S35.

(Configuration example of soft switching start position signal generation circuit)
FIG. 6 is a diagram illustrating a configuration example of the soft switching start position detection circuit 26 in the motor control circuit C illustrated in FIG.
As shown in the figure, the soft switching start position detection circuit 26 compares two input values with the 2-bit shift circuit 60 that shifts the input value S14 by 2 bits to the lower bit side and the counter circuit 61. The comparator circuits 62 and 63 that output the H level only when they are equal, the selector circuit 64, the OR circuit 65, and the flip-flop circuit 66.
FIG. 7 is a timing chart of the main signal in the soft switching start position detection circuit 26, and shows a case where the soft switching start position is set to 75% of the rotor quarter rotation period.

The counter circuit 61 in FIG. 6 counts up at every rising edge of the clock signal S11, and is reset at the rising edge of the clock signal S11 when the rotor 1 rotation edge detection signal S12 and the output S41 of the comparison circuit 62 are at the H level. .
The comparison circuit 62 receives the count value S40 of the counter circuit 61 and a value obtained by dividing the rotor one rotation period by a quarter, and the counter value S40 becomes a quarter of the rotor one rotation period. Sometimes H level. When the output S41 of the comparison circuit 62 becomes H level, the counter circuit 61 is reset and starts counting up from 1.

Since the measured value S14 of the rotation period of the rotor in FIG. 7 is “112”, the quarter value becomes “28”, and the counter circuit 61 is reset when the count value S40 becomes “28”, and “1”. Count up again.
Therefore, the count-up and reset are repeated at the rotor quarter rotation period.
Further, the count value S40 of the counter circuit 61 and the soft switching start position calculation result S15 are input to the comparison circuit 63. When the counter value S40 becomes equal to the soft switching start position calculation result S15, the output S42 is H. Become a level.

As described above, since the measured value S14 of the rotor one rotation cycle in FIG. 7 is “112”, 75% of the rotor one rotation cycle is “84”, which is converted to 75% of the rotor quarter rotation cycle. The soft switching start position calculation result S15 is “21”.
The output S42 of the comparison circuit 63 is a selection signal for the selector circuit 64, and when it is at the H level, the inverted output S45 of the flip-flop circuit 66, and when it is at the L level, the normal output S16 of the flip-flop circuit 66 is output S43. Output as.

The output S43 of the selector circuit 64 becomes the input signal S44 of the flip-flop circuit 66 through a logical sum with the rotor 1 rotation edge detection signal S12.
With the above configuration, the normal output S16 of the flip-flop circuit 66 becomes H level when the rotor one-time edge detection signal S12 is H level, and is a signal that inverts the output at the soft switching start position, that is, The soft switching start position signal S16 is the final output of the soft switching start position detection circuit 26.

The soft switching start position signal S16 in FIG. 7 is already at the H level when the rotor 1 rotation edge detection signal S12 is at the H level, and thus maintains the H level.
Since the soft switching start position calculation result S15 is “21”, when the count value S40 of the counter circuit 61 becomes “21”, the normal output S16 of the flip-flop circuit 66 is inverted and becomes L level. .
The counter circuit 61 is reset when the count value S40 becomes “28”, and starts counting up again from “1”. Therefore, when the count value S40 becomes “21” again, the normal output S16 of the flip-flop circuit 66 is inverted. To H level.

(Operation example)
FIG. 8 is a diagram showing an outline of the soft switching start position detection operation by the motor control device C according to the present invention.
As shown in the figure, a period (time) T1 of one rotation of the rotor 10 is measured from the rotor position detection signal S10, and this time T1 is equally divided by “4” which is the number of magnetic poles of the rotor 10. Is calculated.
As shown in the drawing, the first unit time T2-1 starts from the edge of the rotor position detection signal S10, but ends after a time obtained by dividing the period T1 of one rotation of the rotor 10 into four equal parts. It does not end with the edge of the position detection signal S10.

Then, the next unit time T2-2 starts from the position where the first unit time T2-1 ends, and also ends after a time obtained by equally dividing the period T1 into four from this time point.
Then, the time T3 is further calculated using the unit time T2. Here, the time T3 is set so as to start from the start point of the unit time T2 and end after a period of a fixed ratio with respect to the unit time T2. Here, the period of the constant ratio with respect to the unit time T2 is not particularly limited, but as shown in the figure, for example, about 70 to 80% in consideration of the rise time of the coil current ICOIL. It is desirable to do.

Then, the soft switching start position signal S16 is generated so that the position (time) at which the time T3 ends becomes the soft switching start position.
The soft switching start position signal S16 is used as a rotor position detection signal instead of the original rotor position detection signal S10, and the motor M is driven by the motor control circuit C having soft switching control, as shown in FIG. Coil current ICOIL can be obtained.

(effect)
As described above, the present invention measures the one rotation period T1 of the rotor 10 and sets the time set by using the quarter rotation time of the rotor 10 on the basis of the unit time T2 obtained by dividing the period T1 into four equal parts. T3 is a soft switching start position.
As a result, even when the rotor position detection signal S10 is not an ideal duty 50% output, the soft switching start position signal S16 is always 50% duty, so that the soft switching start position can be accurately detected.

  That is, the soft switching start position signal S16 detected in this way is used as a rotor position detection signal, and the motor M is driven by the motor control circuit C having soft switching control, so as shown in the lower part of FIG. In the technology, even when the rotor position detection signal S10 in question is not ideal duty 50%, it is possible to obtain the coil current ICOIL as shown in the figure, so that low vibration noise and high efficiency of the motor can be achieved.

In the present embodiment, as shown in FIG. 1, an example is shown in which the rotor 10 is a single-phase full-wave brushless DC motor M in which two pairs of four poles, an N pole and an S pole, are used. Of course, the configuration is not limited. That is, for example, when the rotor 10 is configured with three pairs of 6 poles of N and S poles, 4 pairs of 8 poles, ..., n-1 pairs of 2 (n-1) poles, and n pairs of 2n poles. Also, 1/6, 1/8,..., 2 (n-1) / 2, 1 / n, and 1 / n of the rotation period of the rotor are used as the reference, respectively. By setting the switching start position, the soft switching start position signal S16 becomes Duty 50%, and the soft switching start position can be accurately detected.
Further, the control circuit of the present invention can be applied not only to a motor having a single-phase full-wave rectification method, but also to a motor having a single-phase half-wave, a multi-phase full-wave, and a multi-phase half-wave.

It is sectional drawing which shows the structural example of the single phase full wave brushless DC motor M which comprises the motor apparatus 100 of this invention. It is a block diagram which shows the structural example of the motor control circuit C which comprises the motor apparatus 100 of this invention. FIG. 3 is a circuit diagram illustrating a configuration example of a one-rotation edge detection circuit 22 in FIG. 2. FIG. 4 is a timing chart showing the operation of each part of the one-rotation edge detection circuit 22 of FIG. 3. FIG. 3 is a circuit diagram illustrating a configuration example of a soft switching start position calculation circuit 25 in FIG. 2. FIG. 3 is a circuit diagram showing a configuration example of a soft switching start position detection circuit 26 in FIG. 2. It is a timing chart figure of the main signal in motor control circuit C concerning the present invention. It is a timing chart figure which shows the outline of the soft switching start position detection operation in the motor control circuit C concerning this invention, and the conventional soft switching start position detection operation. It is a timing chart figure which shows the outline of the soft switching start position detection operation in a conventional system. It is a timing chart figure which shows the outline of the soft switching start position detection operation which becomes a problem in a conventional system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Motor apparatus 10 ... Rotor 11 ... Bearing 12 ... Stator 13 ... Motor coil 14 ... Hall element 20 ... Rotor position detection circuit 21 ... Oscillator 22 ... 1 rotation edge detection circuit 23 ... 1 rotation cycle counter circuit 24 ... 1 rotation cycle register Circuit 25... Soft switching start position calculation circuit 26... Soft switching start position detection circuit (soft switching start position detection means)
DESCRIPTION OF SYMBOLS 30-32 ... Flip-flop circuit 33-35 ... AND circuit 36 ... Selector circuit 40-44 ... Bit shift circuit 45-48 ... Selector circuit 49 ... Adder circuit 50 ... Soft switching start position setting circuit 60 ... Bit shift circuit 61 ... Counter circuit 62, 63 ... Comparison circuit 64 ... Selector circuit 65 ... OR circuit 66 ... Flip-flop circuit C ... Motor control circuit M ... Single-phase full-wave brushless DC motor

Claims (4)

A motor control circuit comprising means for detecting a soft switching start position based on a detection result of a magnetic pole of a rotating rotor,
The soft switching start position detecting means is
The rotor rotation cycle time is measured based on the magnetic pole detection result of the rotor, and the soft switching start position is detected based on the measured rotor rotation cycle time and the time required for soft switching. Motor control circuit. The motor control circuit according to claim 1,
The soft switching start position detecting means divides the time of one rotation period of the rotor equally by the number of poles of the rotor, and detects the soft switching start position based on the equally divided unit time. Motor control circuit. The motor control circuit according to claim 2,
The soft switching start position detecting means detects a time when 70 to 80% has elapsed from an initial time of the equally divided unit time as the soft switching start position.   A motor apparatus comprising the motor control circuit according to claim 1.

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